Low power cellular modem system architecture

ABSTRACT

In some embodiments, a cellular modem that has reduced power requirements. The cellular modem architecture is divided into three orthogonal domains or modules, these being a control module, an uplink module, and a downlink module. Each of the uplink module and the downlink module is configured to be separately powered down without affecting operation of the other modules.

PRIORITY CLAIM

This application claims benefit of priority of U.S. provisionalapplication Ser. No. 62/307,693, titled “Low Power Cellular Modem SystemArchitecture”, filed Mar. 14, 2016, whose inventors are Moustafa M.Elsayed, Tarik Tabet, Awais M. Hussain, and Lydi Smaini and which ishereby incorporated by reference in its entirety as though fully andcompletely set forth herein.

TECHNICAL FIELD

The present application relates to wireless communication, including animproved cellular modem system architecture with reduced powerconsumption.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further,wireless communication technology has evolved from voice-onlycommunications to also include the transmission of data, such asInternet and multimedia content.

Mobile electronic devices may take the form of smart phones or tabletsthat a user typically carries. Wearable devices (also referred to asaccessory devices) are a newer form of mobile electronic device, oneexample being smart watches. Typically, wearable devices have relativelylimited wireless communications capabilities and typically have smallerbatteries than larger portable devices, such as smart phones andtablets. In general, it would be desirable to reduce the powerrequirements of communication devices, including both wearable devicesand more traditional wireless devices such as smart phones. Therefore,improvements in the field are desired.

SUMMARY

Embodiments are presented herein of, inter alia, a wireless device, suchas a smart watch or phone, with an improved cellular modem systemarchitecture for more efficient communication operations and reducedpower requirements. The cellular modem architecture is divided intothree orthogonal domains or modules, these being a control module, anuplink module, and a downlink module.

The uplink module may comprise an uplink manager processor and anassociated uplink hardware subsystem coupled to the uplink managerprocessor. The downlink module may comprise a downlink manager processorand an associated downlink hardware subsystem coupled to the downlinkmanager processor. In some embodiments, the uplink module comprises afirst plurality of hardware resources and the downlink module comprisesa second plurality of hardware resources, and these first and secondpluralities of hardware resources may be separate such that no hardwareresources are shared between the uplink module and the downlink module.

Each of the uplink module and the downlink module is configured to beseparately powered down without affecting operation of the othermodules. The control module may be configured to selectively power onand/or power off each of the uplink module and the downlink module basedon whether uplink or downlink communications are required. For example,the control manager module may selectively power off the uplink modulewhen uplink communications are not needed, and may selectively power offthe downlink module when downlink communications are not needed. Inaddition, each of the uplink module and the downlink module may beconfigured to selectively power down a subset of its respective hardwarecomponents to reduce power requirements.

The control module, the uplink module and the downlink module may eachcomprise a processor (or “core”) that executes software. In someembodiments the software is architected in a non-hierarchical fashionsuch that the software does not include different hierarchical layers,but rather has a “flat” structure. This reduces overhead andinefficiencies in terms of passing messages between different softwarelayers.

The control module may perform receiving/processing of the downlinkcontrol channel(s). The downlink control channel (the PDCCH) comprisesinformation from the network side that may indicate the downlink and/oruplink operations that the UE should perform. The control modulemonitors the downlink control channel(s) and then initiates operation ofeither the downlink module or the uplink module as appropriate. Forexample, the downlink control channel may indicate that a downlink datachannel is scheduled to contain data targeted for the UE, in which casethe control module may direct the downlink module to power on andmonitor the downlink data channel for the received data. Alternatively,the downlink control channel (the PDCCH) may contain uplink grantsindicating that the UE is being granted permission to perform uplinkcommunications. In this instance, the control module may direct theuplink module to power on at the appropriate time to perform the uplinkcommunications.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of the embodiments is consideredin conjunction with the following drawings.

FIG. 1 illustrates an example wireless communication system includingone or more smart phones and an accessory device;

FIG. 2 illustrates an example system where various UEs, such as a smartphone, accessory device, etc., can communicate with a cellular basestation;

FIG. 3 is a block diagram of an example wireless device;

FIG. 4 illustrates a system architecture according to the prior art;

FIG. 5 illustrates the utilization of control, downlink and uplinkresources of the prior art system architecture of FIG. 4, where theshaded boxes indicate wasted resource usage;

FIG. 6 is a block diagram illustrating an improved system architecturefor a low power wireless device, according to some embodiments;

FIG. 7 is a block diagram illustrating an alternative view of theimproved system architecture for a low power wireless device, accordingto some embodiments;

FIG. 8 is a more detailed block diagram illustrating an improved systemarchitecture for the low power wireless device, according to someembodiments;

FIG. 9 illustrates the utilization of control, downlink and uplinkresources according to the system architecture of FIG. 8 according tosome embodiments; and

FIGS. 10 and 11 illustrate utilization of control, downlink and uplinkresources for a page monitoring use case, according to some embodiments,wherein FIG. 10 illustrates operation according to the prior art systemarchitecture of FIG. 4 and FIG. 11 illustrates operation according tothe system architecture of FIG. 8.

While the features described herein are susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

The term “configured to” is used herein to connote structure byindicating that the units/circuits/components include structure (e.g.,circuitry) that performs the task or tasks during operation. As such,the unit/circuit/component can be said to be configured to perform thetask even when the specified unit/circuit/component is not currentlyoperational (e.g., is not on). The units/circuits/components used withthe “configured to” language include hardware—for example, circuits,memory storing program instructions executable to implement theoperation, etc. Reciting that a unit/circuit/component is “configuredto” perform one or more tasks is expressly intended not to invokeinterpretation under 35 U.S.C. § 112(f) for that unit/circuit/component.

DETAILED DESCRIPTION

Glossary

The following acronyms are used in this disclosure:

PUCCH: Physical Uplink Control Channel

PUSCH: Physical Uplink Shared Channel

PRACH: Physical Random Access Channel

PDCCH: Physical Downlink Control Channel

PDSCH: Physical Downlink Shared Channel

EPDCCH: Enhanced Physical Downlink Control Channel

PCFICH: Physical Control Format Indicator Channel

PHICH: Physical Hybrid-ARQ Indicator Channel

PBCH: Physical Broadcast Channel

PSS: Primary Synchronization Signals

SSS: Secondary Synchronization Signals

UL: Uplink

DL: Downlink

ULM: Uplink Manager

DLM: Downlink Manager

HARQ: Hybrid Automatic Repeat Request

HW: Hardware

TTI: Transmit Time Interval

Terminology

The following are definitions of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DSTM, PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g. smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Wireless Device—any of various types of computer system devices whichperforms wireless communications. A wireless device can be portable (ormobile) or may be stationary or fixed at a certain location. A UE is anexample of a wireless device.

Communication Device—any of various types of computer system deviceswhich performs communications, where the communications can be wired orwireless. A communication device can be portable (or mobile) or may bestationary or fixed at a certain location. A wireless device is anexample of a communication device. A UE is another example of acommunication device.

Base Station—The term “Base Station” (also called “eNB”) has the fullbreadth of its ordinary meaning, and at least includes a wirelesscommunication station installed at a fixed location and used tocommunicate as part of a wireless cellular communication system.

Link Budget Limited—includes the full breadth of its ordinary meaning,and at least includes a characteristic of a wireless device (a UE) whichexhibits limited communication capabilities, or limited power, relativeto a device that is not link budget limited, or relative to devices forwhich a radio access technology (RAT) standard has been developed. A UEthat is link budget limited may experience relatively limited receptionand/or transmission capabilities, which may be due to one or morefactors such as device design, device size, battery size, antenna sizeor design, transmit power, receive power, current transmission mediumconditions, and/or other factors. Such devices may be referred to hereinas “link budget limited” (or “link budget constrained”) devices. Adevice may be inherently link budget limited due to its size, batterypower, and/or transmit/receive power. For example, a smart watch that iscommunicating over LTE or LTE-A with a base station may be inherentlylink budget limited due to its reduced transmit/receive power and/orreduced antenna. Wearable devices, such as smart watches, are generallylink budget limited devices. Alternatively, a device may not beinherently link budget limited, e.g., may have sufficient size, batterypower, and/or transmit/receive power for normal communications over LTEor LTE-A, but may be temporarily link budget limited due to currentcommunication conditions, e.g., a smart phone being at the edge of acell, etc. It is noted that the term “link budget limited” includes orencompasses power limitations, and thus a power limited device may beconsidered a link budget limited device.

Processing Element (or Processor)—refers to various elements orcombinations of elements. Processing elements include, for example,circuits such as an ASIC (Application Specific Integrated Circuit),portions or circuits of individual processor cores, entire processorcores, individual processors, programmable hardware devices such as afield programmable gate array (FPGA), and/or larger portions of systemsthat include multiple processors.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

FIG. 1—Wireless Communication System

FIG. 1 illustrates an example of a wireless cellular communicationsystem. It is noted that FIG. 1 represents one possibility among many,and that features of the present disclosure may be implemented in any ofvarious systems, as desired. For example, embodiments described hereinmay be implemented in any type of wireless device, or any type ofcommunication device. The wireless device embodiment described below isone example embodiment.

As shown, the example wireless communication system includes a cellularbase station 102A, which communicates over a transmission medium withone or more wireless devices 106A, 106B, etc., as well as accessorywireless device 107. Wireless devices 106A, 106B, and 107 may be userdevices, which may be referred to herein as “user equipment” (UE) or UEdevices.

The base station 102 may be a base transceiver station (BTS) or cellsite, and may include hardware that enables wireless communication withthe UE devices 106A, 106B, and 107. The base station 102 may also beequipped to communicate with a network 100 (e.g., a core network of acellular service provider, a telecommunication network such as a publicswitched telephone network (PSTN), and/or the Internet, among variouspossibilities). Thus, the base station 102 may facilitate communicationbetween the UE devices 106 and 107 and/or between the UE devices 106/107and the network 100. In other implementations, base station 102 can beconfigured to provide communications over one or more other wirelesstechnologies, such as an access point supporting one or more WLANprotocols, such as 802.11a, b, g, n, ac, ad, and/or ax, or LTE in anunlicensed band (LAA).

The communication area (or coverage area) of the base station 102 may bereferred to as a “cell.” The base station 102 and the UEs 106/107 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs) or wireless communicationtechnologies, such as GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE-Advanced(LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD),Wi-Fi, WiMAX etc.

Base station 102 and other similar base stations (not shown) operatingaccording to one or more cellular communication technologies may thus beprovided as a network of cells, which may provide continuous or nearlycontinuous overlapping service to UE devices 106A-N and 107 and similardevices over a wide geographic area via one or more cellularcommunication technologies.

Note that at least in some instances a UE device 106/107 may be capableof communicating using any of a plurality of wireless communicationtechnologies. For example, a UE device 106/107 might be configured tocommunicate using one or more of GSM, UMTS, CDMA2000, WiMAX, LTE, LTE-A,WLAN, Bluetooth, one or more global navigational satellite systems(GNSS, e.g., GPS or GLONASS), one and/or more mobile televisionbroadcasting standards (e.g., ATSC-M/H), etc. Other combinations ofwireless communication technologies (including more than two wirelesscommunication technologies) are also possible. Likewise, in someinstances a UE device 106/107 may be configured to communicate usingonly a single wireless communication technology.

The UEs 106A and 106B are typically handheld devices such as smartphones or tablets, but may be any of various types of device withcellular communications capability. The UE 106B may be configured tocommunicate with the UE device 107, which may be referred to as anaccessory device 107. The accessory device 107 may be any of varioustypes of wireless devices, typically a wearable device that has asmaller form factor, and may have limited battery, output power and/orcommunications abilities relative to UEs 106. As one common example, theUE 106B may be a smart phone carried by a user, and the accessory device107 may be a smart watch worn by that same user. The UE 106B and theaccessory device 107 may communicate using any of various short rangecommunication protocols, such as Bluetooth or Wi-Fi.

The accessory device 107 may include cellular communication capabilityand hence is able to directly communicate with cellular base station102. However, since the accessory device 107 is possibly one or more ofcommunication, output power and/or battery limited, the accessory device107 may in some instances selectively utilize the UE 106B as a proxy forcommunication purposes with the base station 102 and hence to thenetwork 100. In other words, the accessory device 107 may selectivelyuse the cellular communication capabilities of the UE 106B to conductits cellular communications. The limitation on communication abilitiesof the accessory device 107 can be permanent, e.g., due to limitationsin output power or the radio access technologies (RATs) supported, ortemporary, e.g., dues to conditions such as current battery status,inability to access a network, or poor reception.

FIG. 2 illustrates a UE device 106 (e.g., a smart phone) and a UEaccessory device 107 in communication with base station 102. Theaccessory device 107 may be a wearable device such as a smart watch. Theaccessory device 107 may comprise cellular communication capability andbe capable of directly communicating with the base station 102 as shown.When the accessory device 107 is configured to directly communicate withthe base station, the accessory device may be said to be in “autonomousmode.”

The accessory device 107 may also be capable of communicating withanother device (e.g., UE 106), referred to as a proxy device orintermediate device, using a short range communications protocol, andmay then use the cellular functionality of this proxy device forcommunicating cellular voice/data with the base station 102. In otherwords, the accessory device 107 may provide voice/data packets intendedfor the base station 102 over the short range link to the UE 106, andthe UE 106 may use its cellular functionality to transmit (or relay)this voice/data to the base station on behalf of the accessory device107. Similarly, the voice/data packets transmitted by the base stationand intended for the accessory device 107 may be received by thecellular functionality of the UE 106 and then may be relayed over theshort range link to the accessory device. As noted above, the UE 106 maybe a mobile phone, a tablet, or any other type of hand-held device, amedia player, a computer, a laptop or virtually any type of wirelessdevice. When the accessory device 107 is configured to indirectlycommunicate with the base station using the cellular functionality of anintermediate or proxy device, the accessory device may be said to be in“relay mode.”

The UE 106 and/or 107 may include one or more antennas for communicatingusing two or more wireless communication protocols or radio accesstechnologies. In some embodiments, the UE device 106/107 might beconfigured to communicate using a single shared radio. The shared radiomay couple to a single antenna, or may couple to multiple antennas(e.g., for MIMO) for performing wireless communications. Alternatively,the UE device 106/107 may include two or more radios. For example, theUE 106 might include a shared radio for communicating using either ofLTE (or LTE-Advanced) or Bluetooth, and separate radios forcommunicating using each of LTE-Advanced and Bluetooth. Otherconfigurations are also possible.

The accessory device 107 may be any of various types of devices that, insome embodiments, has a smaller form factor relative to a conventionalsmart phone, and may have one or more of limited communicationcapabilities, limited output power, or limited battery life relative toa conventional smart phone. As noted above, in some embodiments, theaccessory device 107 is a smart watch or other type of wearable device.As another example, the accessory device 107 may be a tablet device,such as an iPad, with WiFi capabilities (and possibly limited or nocellular communication capabilities) which is not currently near a WiFihotspot and hence is not currently able to communicate over WiFi withthe Internet. Thus, as defined above, the term “accessory device” refersto any of various types of devices that in some instances have limitedor reduced communication capabilities and hence may selectively andopportunistically utilize the UE 106 as a proxy for communicationpurposes for one or more applications and/or RATs. When the UE 106 iscapable of being used by the accessory device 107 as a proxy, the UE 106may be referred to as a companion device to the accessory device 107.

The UE 106 and/or 107 may include a device or integrated circuit forfacilitating cellular communication, referred to as a “cellular modem”.The cellular modem may include one or more processors (processorelements) and various hardware components as described herein. Thecellular modem is described further below. A UE 106 and/or 107 whichincludes the cellular modem may perform any of the method embodimentsdescribed herein by executing instructions on one or more programmableprocessors. Alternatively, or in addition, the one or more processorsmay be one or more programmable hardware elements such as an FPGA(field-programmable gate array), or other circuitry, that is configuredto perform any of the method embodiments described herein, or anyportion of any of the method embodiments described herein. The cellularmodem described herein may be used in a UE device as defined herein, awireless device as defined herein, or a communication device as definedherein. The cellular modem described herein may also be used in a basestation or other similar network side device.

The cellular modem described herein may be particularly advantageous foruse in an accessory UE device, such as a smart watch or other wearabledevice, that is link budget limited. For example, the cellular modem maybe particularly beneficial to devices that are power constrained andwhich can or typically do operate at low data rates.

FIG. 3—Example Block Diagram of a UE Device

FIG. 3 illustrates one possible block diagram of a UE device, such as UEdevice 106 or 107. As shown, the UE device 106/107 may include a systemon chip (SOC) 300, which may include portions for various purposes. Forexample, as shown, the SOC 300 may include processor(s) 302 which mayexecute program instructions for the accessory device 107, and displaycircuitry 304 which may perform graphics processing and provide displaysignals to the display 360. The processor(s) 302 may also be coupled tomemory management unit (MMU) 340, which may be configured to receiveaddresses from the processor(s) 302 and translate those addresses tolocations in memory (e.g., memory 306, read only memory (ROM) 350, Flashmemory 310). The MMU 340 may be configured to perform memory protectionand page table translation or set up. In some embodiments, the MMU 340may be included as a portion of the processor(s) 302.

The UE device 106/107 may also include other circuits or devices, suchas the display circuitry 304, radio 330, connector I/F 320, and/ordisplay 360.

In the embodiment shown, ROM 350 may include a bootloader, which may beexecuted by the processor(s) 302 during boot up or initialization. Asalso shown, the SOC 300 may be coupled to various other circuits of theaccessory device 107. For example, the UE device 106/107 may includevarious types of memory, a connector interface 320 (e.g., for couplingto a computer system), the display 360, and wireless communicationcircuitry 330 (e.g., for communication using cellular, Wi-Fi, Bluetooth,NFC, GPS, etc.).

The UE device 106/107 may include at least one antenna, and in someembodiments multiple antennas 335a and 335b, for performing wirelesscommunication with base stations and/or other devices. For example, theUE device 106/107 may use antennas 335a and 335b to perform the wirelesscommunication. As noted above, the UE may in some embodiments beconfigured to communicate wirelessly using a plurality of wirelesscommunication standards or radio access technologies (RATs).

The wireless communication circuitry 330 may include Wi-Fi Logic 350, aCellular Modem 35, and Bluetooth Logic 354. The Wi-Fi Logic 350 is forenabling the UE device 106/107 to perform Wi-Fi communications on an802.11 network. The Bluetooth Logic 354 is for enabling the UE device106/107 to perform Bluetooth communications. The cellular modem 352 maybe a lower power cellular modem having a system architecture asdescribed herein, and as shown by at least FIGS. 6-8.

As described herein, the cellular modem 352 may include hardware andsoftware components for implementing embodiments of this disclosure. Thecellular modem 352 of the UE device 106/107 may be configured toimplement part or all of the methods described herein, e.g., by aprocessor executing program instructions stored on a memory medium(e.g., a non-transitory computer-readable memory medium), a processorconfigured as an FPGA (Field Programmable Gate Array), and/or usingdedicated hardware components, which may include an ASIC (ApplicationSpecific Integrated Circuit).

FIG. 4—Prior Art Cellular Modem Architecture

FIG. 4 illustrates an architecture of a cellular modem in the prior art.As shown, this example prior art architecture includes first and secondRF (radio frequency) circuitry 402A and 402B. The first RF circuitry402A couples to an L1 Control Core 410, where L1 refers to the PhysicalLayer. The L1 Control Core 410 performs lower Layer 1 control, i.e.,executes “upper layer” software that controls the lower layer driversoftware that interfaces to the hardware. The L1 Control Core 410 mayinclude protocol stack (PS) software or may couple to a PS (ProtocolStack) Core. The L1 Control Core 410 (or Protocol Stack Core) may couplethrough a bus to the Application Processor 302. The second RF circuitry402B couples to a Master Core 422. The Master Core 422 also performslower Layer 1 control and may be implemented in firmware. Thearchitecture may also include a Slave 1 Core 424, which performs lowerLayer 1 control, and a Slave 2 Core 426, which performs upper Layer 1control. The architecture may further include one or more memory pools414, hardware accelerators and/or a power management core 416.

The L1 Control Core 410 performs various tasks, such as: dispatchinghigher layer messages to the corresponding modules/threads;managing/configuring all physical channels including uplink/downlinkchannels and control/data channels; scheduling measurements and RFactivities; performing conflict resolution; and power saving. The L1Control Core 410 has two states, these being “On” and “LowPowerState”,and its duty cycle is such that it is in an “On” state 95% of the time.The L1 Control Core 410 is in the “LowPowerState” in DRX mode.

The Master Core 422 performs various tasks, such as: dispatching L1Control layer messages to the corresponding modules/threads;managing/configuring the hardware components of the physical channelsincluding uplink/downlink channels and control/data channels; schedulingmeasurements and RF activities; scheduling/assigning tasks lists to alleach of the three Cores; reporting results to the L1 Control Core 410;resolving conflicts when using shared resources; and managing powergating/DVFS for all Lower Layer 1 Control and HW-modules. The MasterCore 422 has two states, these being “On” and “LowPowerState”, and itsduty cycle is generally in an “On” state 95% of the time. The MasterCore 422 is in the “LowPowerState” in DRX mode.

The Slave 1 and Slave 2 Cores 424 and 426 perform various tasks, such asconfiguring/controlling hardware components according to the dispatchedtask list and delivering results to the Master Core 422. For each of theSlave Cores 424 and 426, the task list is the only input and the resultsof the individual tasks are the only output. The Slave Cores 424 and 426also have the ability to access hardware components present in thesystem. The Slave 1 and 2 Cores 424 and 426 each have two states, thesebeing “On” and “LowPowerState”, and they are in the “On” state duringtask list execution. The Slave Cores 424 and 426 are in the“LowPowerState” when inactive.

The Memory Pool(s) 414 are shared among the cores and may containvarious buffers, such as a MAC-DL-FIFO, a -MAC-UL-FIFO, anInterprocessor Shared Memory, and Housekeeping memory for scheduling,conflict handling, threads data, etc.

The L1 Control Core 410 and Master Core 424 are configured forbidirectional communication all of the time. Neither of these two coreswith all their associated system resources can be switched off at anytime. These two cores spend a great deal of their time dealing withscheduling, conflict handling, resource management and housekeeping fortheir threads/tasks interactions. This leads to latency in executingpower saving modes and causes the system to be less responsive toLTE-air-interface activities (requests must propagate through threelayers of software down to the hardware which serves the air interface).

For any cellular (e.g., LTE) activity, the two Slave Cores 424 and 426are used to dispatch tasks to the hardware. These two cores cannotdecide whether or not they should be in an off state. As a result, theyspend the most of their life cycles in a “waiting for action” state,executing wait cycles. The memory pools 414 (for hardware Processors)are also in an “on” (“non-off”) state all of the time. The hardware pathis also active during any kind of LTE activity in the air interface.

The prior art cellular modem architecture contains a real time operatingsystem (RTOS) running in the primary core that manages softwareoperations, assigns and distributes threads, etc. These prior artarchitectures also include a scheduler (referred to as L1 control)executing within the L1 Control Core 410 for scheduling operationswithin the single core.

FIG. 5—Example Operation of Prior Art Cellular Modem Architecture

FIG. 5 illustrates an example operation of the prior art cellular modemarchitecture shown in FIG. 4. FIG. 5 illustrates cellular operationsdivided into control tasks, downlink tasks and uplink tasks for ease ofillustration. FIG. 5 illustrates two 1 ms TTIs (Transmit Time Intervals)each with 14 OFDM symbols. During these TTIs the UE is receiving andtransmitting, sometimes in parallel. As shown, the control, downlink anduplink (CTRL, DL, UL) channels are all active. The boxes with dashedlines represent operation of the respective logic after processing,wherein the resources are unused but remain active. All of the resourcesranging from the higher software layers to the hardware (all systemresources) are active whether or not the downlink/uplink is in aprocessing state. The boxes with dashed lines also include the timewasted in issuing requests from an upper software layer/lower softwarelayer and delivering results to the lower software layer/upper softwarelayer synchronized at time interval boundaries. Thus, in the timeline ofFIG. 5 the boxes with dashed lines indicate waste of resource usage,resulting in unnecessary power consumption and reduced battery life.

More specifically, as shown in FIG. 5, the control resources are activeall of the time in their normal power mode—none of the control resourcesare ever powered down or put in a low power mode. In the downlink,during OFDM symbols 0-6 of the first TTI the various downlink resourcesdecode the primary downlink data channel, the PDSCH. After decoding ofthe PDSCH, for OFDM symbols 7-13 the downlink resources are not used butare on and consuming power, as indicated by the dashed box. This isrepeated for the next TTI as shown. In the uplink, during each TTI forapproximately symbols 0-7 in TTI 1 and symbols 0-8 in TTI 2 the uplinkresources are powered on but are not in use.

In prior art architectures, the control, downlink and uplink operationsare all performed in a single core, and hence the downlink and uplinkcannot be selectively powered down when not in use.

Cellular Modem for Low Rate/Low Power Devices

As noted above, certain devices may have one or more of reduced size,reduced battery capability, or reduced power capability relative toother types of devices. Cellular modem chips that are marketed and soldtoday are designed for high data rates and high performance. As aresult, the power consumption of current cellular modem chips isgenerally suboptimal for low power applications and/or devices.Accordingly, there is a need for a low power cellular modem, such as anLTE modem, that is capable of operating with lower power requirementsand/or low transfer rates. There is also a need for a cellular modem fornormal (high data rate) applications that consumes less power thancurrent devices.

Many cellular systems, such as LTE systems, utilize different aspects ofthe system at different time intervals. In other words, downlink anduplink operations are not required to be active all of the time, butrather are in use sometimes and not in use other times. Somecommunication scenarios utilize only some part of the downlink andnothing from the uplink. This behavior may occur, e.g., when the UEsupports half duplex mode.

Cellular activities can thus be thought of as semi-orthogonal, meaningthat uplink activities do not necessarily depend on downlink activities,and vice versa. However, some feedback exists between the uplink anddownlink to guarantee error free reception and transmission. Forexample, a UE may generate channel quality information (CQI) based onreceived downlink transmissions and transmit this CQI information in theuplink to the base station for use in adjusting future downlinktransmissions. However, the feedback that exists between uplink anddownlink operations does not occur at the physical layer, and uplink anddownlink operations are generally separated in time such that uplink anddownlink resources are often not required to both be operating at thesame time.

Cellular (e.g., LTE) modem resources (memory, buses, processors,I/O-interfaces, etc.) are mapped or assigned to the performance ofdifferent cellular (LTE) tasks. Some cellular (LTE) scenarios (paging,airplane mode, data transfer, etc.) can be served by a subset of theresources. In this instance, it would be desirable for the unusedresources to enter a low power state (e.g., off, less clocking, lessvoltage, etc.). Therefore, an improved cellular modem systemarchitecture is desired which is able to opportunistically takeadvantage of scenarios when unused resources are able to be placed in alow power mode.

FIG. 6—Low Power Cellular Modem Architecture

FIG. 6 illustrates a low power cellular modem architecture according tosome embodiments. As shown, the modem is divided into three orthogonaldomains or modules, these being a control module (control managermodule) 502, an uplink module (uplink manager module) 504, and adownlink module (downlink manager module) 506. Each of these modules isdelineated by dashed lines. The control module 502 may comprise acontrol core 512, referred to as the L12Control Manager Core (L12CM),and may also comprise an associated controller hardware subsystem(L12C-HW-Subsystem) 514. The uplink module 504 may comprise an UplinkManager Core (ULM) 522 and associated uplink hardware subsystem(UL-HW-Subsystem) 524. The downlink module 506 may comprise a DownlinkManager Core (DLM) 532, also referred to as the PDSCH (Physical DownlinkShared Channel) Manager Core, and may also comprise an associateddownlink hardware subsystem (DL-HW-Subsystem) 534. The term “Module” asused herein has the full extent of its ordinary meaning and at leastrefers to a collection of one or more processor elements, hardwarecomponents, associated software, memory, etc. The term “Core” as usedherein refers to a “Processing Element” or “Processor” as definedherein.

The L12Control Manager Core (L12CM) 512 is coupled to RF circuitry 516.The RF circuitry 516 is configured for performing RF communications. Thecontrol module 502 (e.g., the L12CM) may couple to a Protocol Stack (PS)Core 546. The uplink module 504 may couple through an Uplink Mac FIFObuffer (UL-MAC-FIFO) 542 to the PS Core 546. The downlink module 506 maycouple through a Downlink Mac FIFO buffer (DL-MAC-FIFO) 544 to the PSCore 546.

FIG. 7—Low Power Cellular Modem Architecture

FIG. 7 illustrates a more detailed block diagram of the cellular modemarchitecture of FIG. 6. FIG. 7 illustrates in greater detail the variousFIFOs used to connect the ULM and the DLM to other parts of the system.As shown, the UL Manager Core (ULM) 522 couples to the L12 ControlManager Core 512 via two FIFOs, these being a ULM-L12CM input FIFO 552and output FIFO 554. Also, the DL Manager Core couples to the L12Control Manager Core 512 via two FIFOs, these being a DLM—L12CM inputFIFO 556 and output FIFO 558.

FIG. 8—Low Power Cellular Modem Architecture

FIG. 8 illustrates a more detailed block diagram of the low powercellular modem architecture of FIGS. 6 and 7, according to someembodiments. As shown and as discussed above, the cellular modem isdivided into three orthogonal domains, these being a control module 502,an uplink module 504, and a downlink module 506 (these referencenumerals are used in FIGS. 6 and 7). The control module 502 comprises acontrol core 512, referred to as the L12 Control Manager Core (L12CM)and associated controller hardware subsystem (L12C-HW-Subsystem) 514.The uplink module 504 comprises an Uplink Manager Core (ULM) 522 andassociated uplink hardware subsystem (UL-HW-Subsystem) 524. The downlinkmodule 506 comprises a Downlink Manager Core (DLM) 532, referred to asthe PDSCH (Physical Downlink Shared Channel) Manager Core, andassociated downlink hardware subsystem (DL-HW-Subsystem) 534. The L12Control Manager Core (L12CM) 512 is coupled to the RF circuitry 516. TheL12 Control Manager Core (L12CM) 512 is also coupled through a ProtocolStack Core 546 to the Application Processor 302 and its associatedinfrastructure.

FIG. 8 shows one example embodiment where each module or domain has asingle core and an associated hardware subsystem. However, it is notedthat in some embodiments one or more of the modules may have a pluralityof cores and/or a plurality of associated hardware subsystems. Forexample, in some embodiments the uplink module 504 may have a pluralityof UL Manager Cores (ULMs) 522 and/or a plurality of UL-HW-Subsystems524. As another example, in some embodiments the downlink module 506 mayhave a plurality of DL Manager Cores (DLMs) 532 (also referred to asPDSCH Manager Cores) and/or a plurality of DL-HW-Subsystems 534. Theseadditional cores/hardware subsystems may be included when a cellularmodem with this system architecture is used in a more traditionalplatform such as a smart phone or tablet, e.g., where low power is notas much a requirement but is still a desirable feature, and high datarates and more advanced features, such as carrier aggregation, aredesired.

The L12C-HW-Subsystem 514 may comprise a plurality of hardwarecomponents, such as (E,M) PDCCH dedicated hardware modules 602, PSS/SSSdedicated hardware modules 604, L12 Control processing memory 606,uplink common hardware modules 606, PCFICH dedicated hardware modules610, PHICH dedicated hardware modules 612, PBCH dedicated hardwaremodules 614, and downlink common hardware modules 616, among possibleothers.

In some embodiments the control module (the L12CM) 512 may be coupled tothe RF circuitry 516. The L12CM 512 may contain the control code for theRF circuitry 516, including code for programming the RF circuitry 516,selectively connecting the other modules (the uplink and downlinkmodules) to the RF circuitry 516 according to timestamps, a calibrationtable for calibrating RF operations, etc. The uplink/downlink commonhardware modules 608 and 616 in the L12C-HW-Subsystem 514 may compriselogic for interfacing to the RF circuitry 516, including ADC/DAC buffers(receive/transmit buffers) which interface to the RF circuitry. Thesereceive/transmit buffers may be shared components among all the threemodules or domains, and the hardware of the three modules may haveaccess to these buffers.

The UL-HW-Subsystem 524 may comprise PUCCH dedicated hardware modules618, an uplink processing module 620, PUSCH dedicated hardware modules622, PRACH dedicated hardware modules 624, and a MAC-uplink FIFO 626.

The DL-HW-Subsystem 534 may comprise PDSCH dedicated hardware modules628, PDSCH processing memory 630, PDSCH HARQ memory 632, and a MAC-PDSCHFIFO 634.

As noted above, each of the ULM 522 and DLM 532 with theirUL/DL-HW-subsystems 524 and 534 have access to the ADC/DAC buffers inthe control module 502. The ADC/DAC buffers are used by the downlinkmodule and uplink module for receiving/transmitting on the RF channel tothe cellular network, e.g., from/to base stations in the cellularnetwork.

Each of these three orthogonal modules or domains 502, 504 and 506 maycomprise a dedicated set of all of the resources (memory, processors,busses, hardware, etc.) that it needs, and these dedicated resources fora particular domain (module) are not shared with other domains (othermodules). If one core is switched off, then consequently all that core'sresources in its own domain may be switched off as well. In other words,when a module is powered down, the core or processing element and all ofits associated hardware resources may be powered down. In someembodiments, one of the uplink module or downlink module may be powereddown without affecting the operation of the other module. In otherwords, the uplink module may be powered down without affecting theoperation of the downlink module, and the downlink module may be powereddown without affecting the operation of the uplink module.

As noted above, instead of having a single monolithic memory used by allof the modules, in some embodiments each module contains the memory thatit needs. Thus when a module is switched off its associated memory isswitched off as well. Memory tends to consume a significant amount ofpower, and the ability to power down a portion of the memory that is notin use results in significant power savings.

Each module (or each core) 502, 504 and 506 may have its owncontrol/configuration software. Each core (processing element) 512, 522and 532 may independently schedule the tasks for the domain's lowerlevel components. The tasks may be scheduled in a hierarchical manner,much like a tree structure with one root and one level of branches. Thearchitecture shown in FIG. 8 has no need for the components as in theother two architectures. As noted above, the three modules 502, 504 and506 are orthogonal, with one aspect of this orthogonality being thateach module can be powered off independently of the other modules.

The control module 502 may be always on when the UE 106/107 is poweredon, and the control module 502 may selectively turn on and power downthe uplink module 504 and downlink module 506 as needed. Note that theterm “power down” may refer to placing them in a low power state orturning these modules completely off. The control module (or the L12CMcore in the control module) thus controls the lifecycle of the uplinkand downlink modules 504 and 506. The LTE-air-interface (the downlinkcontrol channel transmitted by the cellular network) containssequential/parallel control/configuration information for scheduling thereceiving/transmitting of DL/UL data by the UE. The control module 502(e.g., the L12CM) wakes up the uplink module 504 and/or downlink module506, or more precisely wakes up the ULM 522 and/or DLM 532, and deliversconfiguration data to them only if their existence is needed, otherwisethey will be powered off (or powered down).

In at least some embodiments, the system of FIG. 8 has no need for, anddoes not contain, a real time operating system (RTOS) with its overheadand context switching. Each core has a dedicated task, e.g., a controlcore 512 which performs control tasks, an uplink core 522 which performsuplink tasks, and a downlink core 532 which performs downlink tasks.These separate, dedicated orthogonal modules (and associated separatecores) produced the desired parallelism for dealing with UL/DL/Controloperations, and hence there is no need for a RTOS to schedule resourcesfor these different operations.

In at least some embodiments, no resource sharing is performed among thethree modules or domains. In other words, each module or domain isorthogonal to the other domains with respect to its resources. Thecommon resources (resources that are common to both uplink and downlink)belong to L12CM which prepares everything for the other two domains (theUL and DL domains).

L12 Control Manager Core/Module

The L12 Control Manager Core may perform various tasks such as:handling/dispatching of higher layer messages; controlling/configuringL12 downlink control channels (E,M)DPCCH, PCFICH, and PHICH;controlling/configuring common data path hardware components;configuring/controlling PSS/SSS/PBCH; performing measurements;performing channel estimation/loops; managing the L12Control-HW-Subsystem resources and power gating; and controlling the RFhardware. The L12 Control Manager Core may have three states, thesebeing On, Off, and Low Power (LP). The L12 Control Manager Core may bein the On state during all LTE scenarios, except when LTE is in IDLEmode, where the L12 Control Manager Core is in the LP state. The L12Control Manager Core may be in the Off state only when performing a“cold” start. Each of these tasks is discussed in greater detail below.

The L12 Control Manager Core may perform handling and dispatching ofhigher layer (RRC or MAC) messages using flat control code, i.e.,control code without any hierarchical layers. The L12 Control ManagerCore may process all the messages in one single domain (module) and thendispatch the modified versions of the messages to their finaldestination domains (modules). There may be only one receiver permessage, and this receiver may not share any information of the messagewith the other modules. The L12 Control Manager Core may not performstate sharing, which entails that no global scheduling is required, andalso no global resource management is required. Since there is no lowlevel coordination among different modules, power saving decisions arelocal to every domain (or module).

The L12 Control Manager Core may perform receiving/processing of thedownlink control channel(s). The downlink control channel (the PDCCH)comprises information from the network side that may indicate theoperation that the UE should perform. The L12 Control Manager Coremonitors the downlink control channel(s) and then initiates operation ofeither the downlink module or the uplink module as appropriate.

For example, the downlink control channel (the PDCCH) may indicate thata downlink data channel is scheduled to contain data targeted for theUE, in which case the L12 Control Manager Core may direct the downlinkmodule to power on and monitor the PDSCH at the appropriate time for thereceived data. As noted above, the DLM and its associatedDL-HW-Subsystem has access to the ADC/DAC buffers on the control modulewhich are used for receiving and transmitting on the RF channel. Thusthe downlink module can monitor the PDSCH by monitoring those buffers.

In some embodiments, the L12 Control Manager Core may generate aconfiguration for the downlink module which specifies how the downlinkmodule should be configured to receive and process the incoming data.The L12CM may place the configuration in a buffer in the downlinkmodule, whereby when the downlink module wakes up it can access thisconfiguration and configure itself accordingly. The configuration maycomprise the downlink control information (DCI) provided as a

payload on the PDCCH, and may contain instructions or parameters (e.g.,a map) that can be used by the UE to locate and decode its respectivedata in the PDSCH, which is a shared data channel. The configuration maycomprise information about the modulation scheme being used on thePDSCH, transport block size, and other parameters. Stated another way,the PDCCH may include downlink scheduling grant information which isreceived by the L12CM. The L12CM may also receive various higher layerparameters due to its handling of higher layer messages. The L12CM maycombine the downlink scheduling grant information and the higher layerparameters in creating the configuration for use in decoding the PDSCH.

Alternatively, the downlink control channel may contain uplink grantsindicating that the UE is being granted permission to perform uplinkcommunications. In this instance, the L12 Control Manager Core maydirect the uplink module to power on at the scheduled time to performthe uplink communications. The uplink module may generate and providethe uplink data to the ADC/DAC buffers on the control module for uplinktransmission through the RF circuitry. In some embodiments, the L12Control Manager Core may generate a configuration for the uplink modulewhich specifies how the uplink module should be configured in performingthe uplink communications. This configuration may be obtained from thedownlink control information (DCI) provided as a payload on the PDCCH,which contains the uplink scheduling grant information. Thisconfiguration may comprise instructions or parameters (e.g., a map) thatcan be used by the UE to encode and transmit on the PUSCH. Theconfiguration may comprise information about the modulation scheme beingused on the PUSCH, transport block size, and other parameters. Statedanother way, the PDCCH may include uplink scheduling grant informationwhich is received by the L12CM. The L12CM may also receive varioushigher layer parameters due to its handling of higher layer messages.The L12CM may combine the uplink scheduling grant information and thehigher layer parameters in creating the configuration for use indecoding the PUSCH.

as well as various higher layer parameters that are provided for use intransmitting uplink data on the PUSCH.

In some embodiments, the L12 Control Manager Core may monitor thefollowing channels: (E,M) PDCCH, PCFICH, PHICH. The term “(E,M) PDCCH”refers to the PDCCH, the EPDCCH and the MPDCCH. The PDCCH is the primarychannel that is monitored by the control module (the L12 MC) as thischannel contains information regarding what downlink/uplink operationsare to be performed. The L12 Control Manager Core may use informationobtained in the PDCCH to selectively power on/power down the uplink anddownlink modules to perform certain tasks or go to sleep. The L12Control Manager Core may also monitor the PCFICH (Physical ControlFormat Indicator Channel), which contains the control channel format forthe PDCCH and the PHICH, and the PHICH (Physical Hybrid-ARQ IndicatorChannel), which contains HARQ acknowledgements.

The L12 Control Manager Core may configure its L12CM-HW-Subsystem toreceive L1/L2 downlink common control channels. As noted above, thecontrol information received by the L12 Control Manager Core may bedispatched to the ULM or/and DLM cores only if required. In someembodiments, the L12 Control Manager Core may initiate, or power on or“wake up” the uplink and downlink modules using respective interrupts.

The L12 Control Manager Core may control/configure the common componentsof the uplink and the downlink. In other words, the control module,e.g., L12 Control Manager Core and its associated hardware subsystem,may contain certain hardware and/or software functionality that iscommon to uplink communications and other functionality that is commonto downlink communications. For different physical channels, this commonfunctionality may be configured and controlled by L12CM without wakingup the other two cores ULM/DLM with their respective HW domains. Thecommon uplink/downlink functionality might be for example scrambling,certain aspects of rate matching, etc.

The L12 Control Manager Core may control the timing of waking up the ULMand DLM cores. Upon reception of any scheduling assignment for DL asdetermined by monitoring the PDCCH, the L12 Control Manager Core maydetermine a DL-configuration for the DLM core and place this DLconfiguration in a buffer in the downlink module. The L12CM then wakesup the DLM core (possibly with a new interrupt to the DLM) just prior towhen the downlink module is needed to monitor the PDSCH to receive andperform DL processing on the incoming DL data on the PDSCH. In otherwords, the L12CM may receive an indication of the arrival of downlinkdata on the PDCCH and create and store a configuration in a buffer ofthe downlink module, but the L12CM may only wake up the downlink module(the DLM core) just prior to when the data is scheduled to appear on thePDSCH. This results in power savings, since the downlink module is notunnecessarily consuming power while waiting for its data to arrive.Similarly, if the L12 Control Manager Core receives uplink schedulinggrants, it may create a configuration for the ULM core and place this ULconfiguration in a buffer in the Uplink module. The L12CM then wakes upthe ULM core (e.g., with an appropriate interrupt) just prior to whenthe uplink communication is scheduled to perform the processing of thetransport block for UL transmission. Again, this results in powersavings, since the uplink module is not unnecessarily consuming powerwhile waiting to perform its uplink communications pursuant to thereceived uplink grant. Thus the L12CM essentially performs a “just intime” wake up of each of the DL and UL modules.

The L12 Control Manager Core may perform common signal processing, suchas channel estimation, automatic gain control (AGC), TTL, FTL, Loops andmeasurements.

The L12 Control Manager Core may operate to configure/control the RFhardware. The L12 Control Manager Core may be the only core to configureand control the RF, and may have a single module to perform this task.In some embodiments, switching on/off the RF hardware is done locally bythe L12 Control Manager Core. Thus the power saving modes can be applieddependent on the particular scenario. Making RF decisions locally leadsto fast application of those decisions without requiring coordinationwith any other modules.

The L12 Control Manager Core may perform control the L12C-HW-Susbsystem,and in particular the power gating (or powering up/down) of hardwarecomponents in the L12C-HW-Susbsystem. In other words, the L12 ControlManager Core may have the ability to turn on/off individual hardwarecomponents of the L12C-HW-Susbsystem. If the L12CM core sees, accordingto its sole scheduling, that any hardware module of theL12C-HW-Susbsystem is not needed, it may switch this hardware module off(i.e., power down this hardware module).

The L12 Control Manager Core may operate to process the PSS/SSS/PBCH inorder to ensure the UE stays synchronized to the network. The PSS(Primary Synchronization Signals), the SSS (Secondary SynchronizationSignals) and the PBCH (Physical Broadcast Channel) are transmitted bythe network and used by the UE to maintain synchronization with thenetwork. These synchronization signals are not related to either uplinkor downlink transmission, and thus are handled in the control module.The control module processes the PSS/SSS/PBCH without the need to wakeup the uplink or downlink modules.

The L12 Control Manager Core may have only one layer of software inside.Accordingly, there may be only one entity (L12Control) whichdecides/requests/executes/evaluates the various operations performed inthe core. The core thus also may have no latency with respect to itsassociated HW-Subsystem. Since the L12 Control Manager Core implements aflat software system (software without hierarchical layers), powersaving decisions may be relatively easy, and no interaction amongdifferent entities may be needed to decide whether a resource needs tobe off, on, or in low power mode.

Control Domain (L12CM and its Domain)—Problems and Solutions: SystemAspect

The following describes certain problems associated with the prior artarchitecture of FIG. 4 from a “system” point of view, i.e., from theperspective of the software architecture and system resources.

In the prior art architecture:

Horizontal software layers perform scheduling and thinking for lowerlayers; this results in coordination overhead between the layers anddelays due to resource conflict scheduling.

Software layers may be mapped either to processors or to separatethreads. A layer communicates with another layer through shared memoryaccompanied by interrupts or through a RTOS FIFO;

DL, UL, and Control functionality exist in every software layer but withdifferent types of abstraction. To resolve conflicts on system resourcesin every layer, either multiple threads are used or alternatively aconflict handler is used with a number of registering tables;

Results are propagated from lower levels to upper levels causing delaysin feedback loops;

Power is consumed in the bus and dual memory is required forinter-processor communication even when the processors are notcommunicating.

The following describes certain advantages of the improved cellularmodem architecture shown in FIG. 8 from a “system” point of view, i.e.,from the perspective of the software architecture and system resources.These advantages may be present in certain embodiments, and may not bepresent or required in other embodiments. In the improved low powercellular modem architecture according to some embodiments:

There may be no software layers. In other words, the software hierarchymay be flat, which may remove software overhead associated with messagepassing between layers and delays due to inter-layer coordination andcommunication. The elimination of software layers may also remove theneed for FIFOs and shared memories to interface between the layers. Thismay also reduce the total amount of software used in the system, whichin some embodiments is roughly half the amount used in prior artsystems.

Every core may have its own scheduler, and scheduling one core may beunrelated to scheduling of another core. Thus a respective core, such asthe UL or DL core, can schedule its own resources in an improved mannerwithout interference from another module.

No global resource management or global conflict handling may beperformed. Each module may have its own set of dedicated resources,which may remove resource conflict issues. Decisions to forward messagesor data may be performed quickly, and thus power switching modes can bedone with reduced latency.

The device may not require or utilize a RTOS with all of its resourcesand associated overhead. Thus cycles are not wasted in performingcontext switching and other overhead associated with an operatingsystem.

The device may have less memory and less cores, saving power and area.For example, in some embodiments the cellular modem does not employcache systems for at least the uplink and downlink modules. The memoryin each of the uplink and downlink modules may be sufficiently smallsuch that caches are not needed. In one embodiment the total amount ofmemory used in all of the modules is 1 Mbyte.

Results produced by a core may remain in that core e.g., the uplinkmodules may not be required to share their results with the downlinkmodules, and vice versa. Feedback decisions can be taken locally. Powersaving modes depending on results can be done without latency, e.g., amodule may be quickly powered down once its task is complete. Forexample, the control module may quickly power down the UL or DL moduleafter it has completed its task, e.g., after the UL/DL module hascompleted its interrupt service routine and notified the control moduleof its completion. Alternatively, in some embodiments, when either theUL or DL module completes a task the UL or DL module may have theability to independently power itself down without seeking permissionfrom the control module.

The bus and the dual shared memory may be used only when more than onecore is active. If only one module is active, then there may be no needfor a common bus (an inter-module bus) to be active, since the activemodule has no need to communicate on the bus with the other inactivemodules. If in some embodiments a shared memory exists to all the UL andDL cores to pass messages or data to each other, if only one module isactive then there may be no need for this shared memory to be active,since the active module has no need to utilize the shared memory tocommunicate with the other inactive modules.

The following describes power saving aspects of the low power cellularmodem architecture from a “system” point of view according to someembodiments. The improved low power cellular modem architecture may havethe following characteristics according to some embodiments:

Physical separation of sequential and orthogonal tasks, which allows forsequential/partial powering on of hardware components. In other words,the architecture may be such that the UL and DL modules will generallyoperate in a sequential manner, thus allowing one to be powered downwhile the other is operating. The architecture design may also operateto save power even in the scenario where the DL and UL must be on allthe time, due at least in part to the flat (non-hierarchical) softwarestructure, reduced inter-system communication and bus usage, and otherimprovements described herein.

Elimination of housekeeping/overhead software which may prevent thesystem from making/taking fast power mode decisions/actions. Thisincludes the elimination of an operating system and well as softwarelayering.

Reduction of wasted resources used for conflict handling/layer orientedscheduling and interprocessor communication. This may also result inless code memory, less caches, and less data memory.

Control Domain (L12CM and its Domain)—Problems and Solutions:Functionality Aspect

The following describes certain problems associated with the prior artarchitecture of FIG. 4 from a “functionality” point of view.

With respect to Higher Layer Message Handling:

In the prior art architectures: the entire modem is in the On statevirtually all of the time; three separate modules are involved inprocessing messages, these being the message handler, the activityscheduler, and the power saving scheduler; and different versions of themessage propagate from L1C→FW→HW-Driver.

In the Low Power Architecture in some embodiments: the L12CM is in theOn state most of the time, whereas the ULM and DLM may not be. Thecontrol module may have a single core that processes messages, whichdiffers from the three separate modules discussed in the aboveparagraph. This may reduce inter-process communication and otheroverhead. Also, there may be no need for an activity/sleep scheduler.Instead the control core may control the power state of the uplink anddownlink cores. Further, the software architecture may be flat, with nolayering—only one flat module may handle/process messages.

The power saving aspect of the Low Power Architecture may be at least asfollows in some embodiments: only portions or subsets of the modem maybe required to be powered on at any given time; flat software withouthierarchical layering may result in fast power saving decisions; andconflict/scheduling software may not be needed, resulting in less MIPSrequirements and less memory.

With respect to Receiving/Processing of Control PHY Channels:

In the prior art architectures: the entire modem is in the On statevirtually all of the time; all the software and the cores are involvedin receiving and processing PDCCH; in the case of transitioning to a lowpower state after PDCCH/PSS/SSS/PBCH, the request propagates throughdifferent layers causing a latency due to inter-layer communication.

In the Low Power Architecture in some embodiments: only the L12CM is inthe On state most of the time; only a single module may be used percontrol PHY channels, and no housekeeping software may be involved; andwhen the module (domain) has completed its processing, the module andall of its lower components can enter the off-state.

The power saving aspect of the Low Power Architecture may be at least asfollows in some embodiments: only portions or subsets of the modem maybe required to be powered on at any given time; the design of orthogonalmodules enables fast power saving decisions; and separate treestructures with decisions on the root enables power mode decisions to beeasily applied downward to various hardware components.

With respect to Common Signal Processing/RF Control:

In the prior art architectures: the entire modem is in the On statevirtually all of the time; different modules and cores are involved insignal processing; results are propagating upward to higher softwarelayers, e.g., HW-driver→FW→L1C. Utilizing the results involvespropagating the results downward to lower software layers, whichnecessitates a large amount of software involvement.

In the Low Power Architecture in some embodiments: only the L12CM may bein the On state most of the time; only a single module may be used persignal processing aspect; the results may be buffered, post-processed,and applied by the same entity (or module); and no interveninghandler/layer may be used in some embodiments.

The power saving aspect of the Low Power Architecture may be at least asfollows in some embodiments: only portions or subsets of the modem maybe required to be powered on at any given time; no copying of large datamay be needed, rather one entity (one module) has the results, thusrequiring less memory; and different modules or portions of the cellularmodem can start/stop quickly.

UL Manager Core (ULM) Domain

The UL Manager Core (ULM) may perform various tasks in some embodiments,such as: scheduling for uplink activities; controlling/configuringuplink physical channels PUCCH, PUSCH, and PRACH;controlling/configuring the uplink dedicated data path; managingUL-HW-Subsystem resources and power gating; and managing the MAC uplinkbuffer. The UL Manager Core (ULM) may have two states, these being Onand Off. The UL Manager Core (ULM) may be in the On state duringPUCCH/PUSCH activities. The UL Manager Core (ULM) may be in the Offstate if uplink communication is completed or there is no uplink. Eachof these tasks is discussed in greater detail below.

The ULM may perform scheduling for uplink activities. The L12CM may wakeup the ULM only in the instance when there is an uplink grant. The L12CMmay also deliver to the ULM the configuration as well (for the PUSCH usecase). Similarly, the L12CM may deliver to the ULM the configuration ifa PRACH is scheduled or PUCCH transmission is to occur. The ULM core mayschedule the tasks for the uplink-dedicated SW modules, and thescheduled software modules may configure/control the Uplink Hardwarecomponents. As soon as the transport block is transmitted, the ULM maythen switch off all the resources lying in its domain.

The memory managed by the ULM may include uplink processing memory andthe DL-MAC-FIFO (Downlink Media Access Control FIFO). The hardwarecomponents managed by the ULM may include the PUCCH data path, the PUSCHdata path, and the PRACH data path. Alternatively, in some embodimentsthe ULM may control/execute only the PUSCH channel, and the PUCCH andPRACH processing may be moved to the L12CM core. The architecturedescribed herein is thus very flat (non-hierarchical), where most or allof the signal processing of the inner receiver and the PHY controlchannels may be concentrated in the L12CM core, and in some embodimentsthe ULM and DLM only operate with the physical (PHY) data channels. Thisis especially useful in the case where DL activity occurs with only anACK/NACK being received in the UL. In that case only 2 cores need to beawakened.

When transmitting uplink, the ULM and all of its domain may be poweredon for less than one slot. The system may consume approximately 40% ofthe power of a traditional prior art architecture where the uplinkoperates until the end of the TTI (Transmit Time Interval). When thereis no uplink to be scheduled, the ULM and all its domain is powered off.This results in 0% power consumption, as compared to a prior artarchitecture that allows the uplink domain to run until the end of theTTI and thus unnecessarily consumes power during this time.

DL Manager Core (DLM) Domain (PDSCH Manager Core)

The Downlink Manager Core (DLM) (or PDSCH Manager Core) may performvarious tasks such as: scheduling for downlink activities;controlling/configuring the downlink physical channel—PDSCH;controlling/configuring the downlink dedicated data path; managingPDSCH-HW-Subsystem resources and power gating; and managing the MACdownlink buffer. The PDSCH Manager Core (DLM) may have two states, thesebeing On and Off. The PDSCH Manager Core (DLM) may be in the On stateduring PDSCH activities, and may be in the Off state if PDSCH processingis being performed or there is no PDSCH.

The DL Manager Core may perform scheduling for PDSCH activities. TheL12CM may wake up the DLM only in the instance when there is ascheduling assignment. The L12CM may also deliver to the DLM theconfiguration to be used for the DL communication. The DL Manager Coremay schedule the tasks for the PDSCH-dedicated SW modules, and thescheduled modules may configure/control the DL hardware components. Whenthe transport block is received on the downlink, the DLM may insert theblock into the DL-MAC-FIFO. After receiving the transport block on thedownlink and inserting the block into the DL-MAC-FIFO, the DLM may thenswitch off all the resources lying in its domain.

The memory managed by the DLM may include the PDSCH processing memory,the HARQ buffer, and the DL-MAC-FIFO. The hardware components managed bythe DLM may include the LLR buffer, rate matching logic, and turbodecoder logic, among others.

When receiving data on the PDSCH, the DLM and all of its domain may bepowered on for one slot. The system may consume 50% of the power of aprior art architecture that allows the PDSCH domain to operate until theend of the TTI. When the PDSCH is not scheduled to be received, the DLMand all its domain may be powered off. This results in very low (near0%) power consumption, as compared to a prior art architecture whichallows the PDSCH-domain to operate until the end of the TTI and thusunnecessarily consumes power during this time.

FIG. 9—Cellular Modem Low Power Architecture Use Case

FIG. 9 illustrates a timeline that shows a use case for the low powercellular modem architecture according to some embodiments, where boththe uplink (UL) and downlink (DL) are active. This is an excerpt of ageneral use case where data is transmitted and received, such as in aVoLTE call, utilizing x Mbps downlink and y Mbps uplink at the sametime.

As shown, the L12CM domain (Control Tasks and Resources) may be activeto receive the control information and deliver them to both the DLM andULM. The L12CM domain may perform all the tasks related to signalprocessing of the inner receiver and to the common transmit/receiveportion.

As shown, the L12CM may wake up the DLM directly prior to OFDM symbol 0to process the PDSCH. The DLM may then spend 7 OFDM symbols (symbol 0 tosymbol 6) processing the PDSCH. In OFDM symbol number 6, the DLM mayswitch off its domain and go into sleep mode.

As shown, at OFDM symbol 0 the ULM may switch off its domain and entersleep mode. The L12CM may wake the ULM at OFDM symbol 8, which is 6slots before the transmission of the uplink.

Referring again to FIG. 5, the wasted resources are delineated withboxes having dashed lines. The prior art architectures in FIG. 4 cannotswitch off resources because of the various software complexitiesinvolved, including the software layering, sharing of hardwareresources, and the RTOS.

FIGS. 10 and 11—Cellular Modem Low Power Architecture Paging Use Case

FIGS. 10 and 11 illustrate contrasting examples of a timeline that showsa paging use case for the low power cellular modem architecture ascompared to a traditional prior art architecture, according to someembodiments. FIG. 10 is a timeline that shows operation of thetraditional prior art cellular modem architecture of FIG. 4 performing apaging operation. FIG. 11 is a timeline that shows operation of the lowpower cellular modem architecture of FIG. 8 performing a pagingoperation in some embodiments.

During page monitoring, the UE may decode the PDCCH followed by thePDSCH in order to determine whether or not there is a paging (incomingphone call) designated for the UE. If there is no paging, then the UEmay go into a sleep mode for a specified number of LTE frames.

As shown in the timeline of FIG. 10, using the traditional prior artcellular modem architecture of FIG. 4, power is unnecessarily consumedby housekeeping resources for the downlink (downlink resources,memories, buses, processors, and other hardware), and also power isunnecessarily consumed by housekeeping resources for the uplink (uplinkresources, memories, buses, processors, and other hardware). Furthereach of the downlink and uplink hardware have undesirable propagationlatencies that further consume power.

As shown in the timeline of FIG. 11, using in the low power cellularmodem architecture (LP LTE architecture) of FIGS. 6-8, the DLM mayoperate with reduced power requirements. In particular, decoding andprocessing of the PDSCH may occur during the second set of OFDM symbols0-6 and can otherwise be turned off. The ULM and all of its resourcesmay not be started at all since they are not necessary when decoding anincoming paging message.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A modem for use in wireless communications,comprising: a control manager module comprising a control processor andan associated control hardware subsystem coupled to the controlprocessor; an uplink manager module, wherein the uplink manager moduleis coupled to the control manager module, wherein the uplink managermodule is configured for use in performing wireless uplinkcommunications, and wherein the uplink manager module comprises anuplink processor and an associated uplink hardware subsystem coupled tothe uplink processor; and a downlink manager module, wherein thedownlink manager module is coupled to the control manager module,wherein the downlink manager module is configured for use in performingwireless downlink communications, and wherein the downlink managermodule comprises a downlink processor and an associated downlinkhardware subsystem coupled to the downlink processor; a port coupled tothe control manager module and configured for coupling to radiofrequency (RF) communication circuitry; wherein the control managermodule is configured to monitor a downlink control channel to obtainscheduling information regarding what downlink or uplink operations areto be performed; wherein each of the uplink manager module and thedownlink manager module is configured to be separately powered down bythe control manager module without affecting operation of the other ofthe uplink manager module and the downlink manager module, and whereinsaid powering down is performed based on the scheduling informationobtained from the downlink control channel, wherein powering down theuplink manager module comprises turning off the uplink processor,wherein powering down the downlink manager module comprises turning offthe downlink processor, wherein turning off the uplink processoroperates to power down hardware resources in the associated uplinkhardware subsystem, and wherein turning off the downlink processoroperates to power down hardware resources in the associated downlinkhardware subsystem, wherein each of the control manager module, theuplink manager module, and the downlink manager module comprises its ownconfiguration software, wherein the configuration software in each ofthe control manager module, the uplink manager module, and the downlinkmanager module independently schedules tasks for its respective moduleusing respective hardware resources in its associated hardwaresubsystem, wherein the configuration software in each of the controlmanager module, the uplink manager module, and the downlink managermodule does not comprise hierarchical layers, and wherein the controlmanager module is configured to separately power down the uplink managermodule and the downlink manager module without conducting globalscheduling and global resource management.
 2. The modem of claim 1,wherein the control manager module is configured to selectively power onand power off each of the uplink manager module and the downlink managermodule based on whether uplink or downlink communications are required.3. The modem of claim 1, wherein the control manager module isconfigured to selectively power off the uplink manager module whenuplink communications are not needed; wherein the control manager moduleis configured to selectively power off the downlink manager module whendownlink communications are not needed.
 4. The modem of claim 1, whereinthe uplink manager module is configured to be separately powered downfrom the downlink manager module such that the downlink manager modulecan operate while the uplink manager module is powered down; wherein thedownlink manager module is configured to be separately powered down fromthe uplink manager module such that the uplink manager module canoperate while the downlink manager module is powered down.
 5. The modemof claim 1, wherein the uplink manager module comprises a firstplurality of hardware resources configured to perform uplink tasks;wherein the downlink module comprises a second plurality of hardwareresources configured to perform downlink tasks; wherein the firstplurality of hardware resources is separate from the second plurality ofhardware resources such that no hardware resources are shared betweenthe uplink module and the downlink module.
 6. The modem of claim 1,wherein the uplink processor is configured to selectively turn offcertain hardware components in the uplink hardware subsystem that arenot being used in uplink communications; wherein the downlink processoris configured to selectively turn off certain hardware components in thedownlink hardware subsystem that are not being used in downlinkcommunications.
 7. The modem of claim 1, wherein the control hardwaresubsystem comprises common hardware resources that are utilized for bothuplink and downlink communications.
 8. The modem of claim 1, wherein themodem is a cellular modem configured for use in performing cellularuplink and downlink communications with a cellular base station.
 9. Themodem of claim 1, wherein the control manager module is configured toreceive a downlink communication in a wireless manner and store receiveddata from the downlink communication in a memory in the downlink managermodule for processing by the downlink manager module; wherein the uplinkmanager module is configured to receive transmit data intended foruplink transmission and store the transmit data in a memory on thecontrol manager module for uplink transmission to a base station. 10.The modem of claim 1, wherein the modem is comprised on a singleintegrated circuit.
 11. A wireless device, comprising: radio frequency(RF) circuitry for performing RF communications; a modem comprising: acontrol manager module comprising a processor core and a controlhardware subsystem configured to handle control communications accordingto a wireless communication technology, wherein the control managermodule is coupled to the RF circuitry; a downlink manager modulecomprising a processor core and a downlink hardware subsystem configuredto handle downlink data communications according to the wirelesscommunication technology, and wherein the downlink manager modulecomprises a downlink processor and an associated downlink hardwaresubsystem coupled to the downlink processor; and an uplink managermodule comprising a processor core and an uplink hardware subsystemconfigured to handle uplink data communications according to thewireless communication technology, and wherein the uplink manager modulecomprises an uplink processor and an associated uplink hardwaresubsystem coupled to the uplink processor; wherein the RF circuitry, thecontrol manager module, the downlink manager module, and the uplinkmanager module are communicatively coupled; wherein the control managermodule is configured to monitor a downlink control channel to obtainscheduling information regarding what downlink or uplink operations areto be performed; wherein each of the uplink manager module and thedownlink manager module is configured to be separately powered down bythe control manager module without affecting an ability of the other ofthe uplink manager module and the downlink manager module to perform itsrespective tasks, and wherein said powering down is performed based onthe scheduling information obtained from the downlink control channel,wherein powering down the uplink manager module comprises turning offthe uplink processor, wherein powering down the downlink manager modulecomprises turning off the downlink processor, wherein turning off theuplink processor operates to power down hardware resources in theassociated uplink hardware subsystem, and wherein turning off thedownlink processor operates to power down hardware resources in theassociated downlink hardware subsystem, wherein each of the controlmanager module, the uplink manager module, and the downlink managermodule comprises its own configuration software, wherein theconfiguration software in each of the control manager module, the uplinkmanager module, and the downlink manager module independently schedulestasks for its respective module using respective hardware resources inits associated hardware subsystem, wherein the configuration software ineach of the control manager module, the uplink manager module, and thedownlink manager module does not comprise hierarchical layers, andwherein the control manager module is configured to separately powerdown the uplink manager module and the downlink manager module withoutconducting global scheduling and global resource management.
 12. Thewireless device of claim 11, wherein the control manager module isconfigured to selectively power on and power off each of the uplinkmanager module and the downlink manager module based on whether uplinkor downlink communications are required; wherein the control managermodule is configured to selectively power off the uplink manager modulewhen uplink communications are not needed; wherein the control managermodule is configured to selectively power off the downlink managermodule when downlink communications are not needed.
 13. The wirelessdevice of claim 11, wherein the uplink manager module comprises a firstplurality of hardware resources; wherein the downlink manager modulecomprises a second plurality of hardware resources; wherein the firstplurality of hardware resources is separate from the second plurality ofhardware resources such that no hardware resources are shared betweenthe uplink manager module and the downlink manager module.
 14. Thewireless device of claim 11, wherein the control hardware subsystemcomprises common hardware resources that are utilized for both uplinkand downlink communications.
 15. A method, comprising: by a modemconfigured for inclusion within a wireless device, the modem comprising:a control manager module comprising a control processor and anassociated control hardware subsystem coupled to the control processor;an uplink manager module configured for use in performing wirelessuplink communications, wherein the uplink manager module comprises anuplink processor and an associated uplink hardware subsystem coupled tothe uplink processor; a downlink manager module configured for use inperforming wireless downlink communications, wherein the downlinkmanager module comprises a downlink processor and an associated downlinkhardware subsystem coupled to the downlink processor; and a portconfigured for coupling to radio frequency (RF) communication circuitry;wherein the uplink manager module, the downlink manager module, and theport are coupled to the control manager module, the method comprising:monitoring, by the control manager module, a downlink control channel toobtain scheduling information regarding what downlink or uplinkoperations are to be performed; separately powering down, by the controlmanager module, at least one of the uplink manager module and thedownlink manager module without affecting operation of the other of theuplink manager module and the downlink manager module, wherein saidpowering down is performed based on the scheduling information obtainedfrom the downlink control channel, and wherein said powering down isperformed without conducting global scheduling and global resourcemanagement, wherein powering down the uplink manager module comprisesturning off the uplink processor, wherein powering down the downlinkmanager module comprises turning off the downlink processor, whereinturning off the uplink processor operates to power down hardwareresources in the associated uplink hardware subsystem, wherein turningoff the downlink processor operates to power down hardware resources inthe associated downlink hardware subsystem, wherein each of the controlmanager module, the uplink manager module, and the downlink managermodule comprises its own configuration software, wherein the methodfurther comprises, by the configuration software in each of the controlmanager module, the uplink manager module, and the downlink managermodule: independently scheduling tasks for the respective module usingrespective hardware resources in the respective associated hardwaresubsystem wherein the configuration software in each of the controlmanager module, the uplink manager module, and the downlink managermodule does not comprise hierarchical layers.
 16. The method of claim15,wherein the control hardware subsystem comprises common hardwareresources that are utilized for both uplink and downlink communications.